Composite particles for controlling arthropod infestation

ABSTRACT

Composite particles comprising baculovirus particles in a coating of wax that is degradable in the gut of a larva of an arthropod species, optionally in conjunction with an insecticide, methods of manufacture, uses thereof, and methods of controlling arthropod infestations.

The present invention relates to compositions, particles and usesthereof, methods for controlling pests and methods of producingcompositions and particles for the control of pests. In particular, theinvention relates to compositions and particles comprisingentomopathogenic viruses, their uses on plant material, methods forcontrolling pests with entomopathogenic viruses, and processes forproducing particles and particles of use in controlling pests employingsuch organisms.

The human population of the world is increasing and is expected toplateau by 2030 at about 9 billion. As the population increases there isan ever expanding need to produce more food to feed it, andconcomitantly, farmed animals such as livestock, fish, poultry and otheranimals on which the human population depends, at least in part. Much ofthe food source that is required for humans, livestock and other farmedanimals is provided in the form of plants and plant-derived matter fromcultivated cereals, vegetables, fruit bearing plants such as bushes,strawberries, raspberry canes, gooseberries, vines such as grape vines,passionfruit and kiwifruit and the like, and trees for nuts such ashazelnuts, almonds, walnuts, brazil nuts, cashew nuts and the like; oilgeneration from trees such as palm oil, nut oils and the like; and fruitproduction from trees such as citrus fruits, apples, pears, peaches,plums, mangoes, papayas, and the like. Other plant resources that areused and/or cultivated by mankind include woody plants such as trees forwood e.g. for use in building construction, boat building, furnituremanufacture and fencing; plants cultivated for the production ofclothing materials, such as cotton, hemp and linen and the like.

Plants of agronomic importance to man are constantly open to attack frompests such as arthropods which deposit eggs on aerial parts andunderground parts of the plants. The eggs hatch into larvae which thenfeed on the plants leading to lower yields per unit area of farmed landand increased numbers of newly generated arthropods. If left unchecked,resultant economic losses are significant, and may become substantial orin major crop infestations may result in the loss of entire crops.

It is a constant battle to keep one step ahead of arthropod evolutionand/or to maintain or improve arthropod controlling activities where theuse of chemicals over time indicates that arthropod species aredeveloping resistance.

One problem associated with the conventional use of chemical agentsprovided in liquid form against arthropods in the field is that whilethe chemical agents provided may be effective for short periods of timeafter application, over longer periods of time, the level of activitytends to drop off and/or target pests develop resistance. As a result,the user has to apply chemicals more frequently in order to maintaincontrol over arthropod infestation. This in turn means that the environsto which the chemicals are applied will receive high chemical loadsoften and this may have an adverse effect on the environment, and inparticular on animals such as mammals, including humans, as well asother kinds such as birds, amphibians, and beneficial arthropods such asbees, aphid-eating ladybirds, spiders and butterflies.

Biological agents have been used in the past and are used today tocontrol insect pests.

Certain biological agents that have proven useful in the control ofarthropods on crops include the invertebrate-specific baculoviruses. Thebaculoviruses are circular DNA viruses that can be divided into fourgenera: Alphabaculovirus (lepidopteran-specific nucleopolyhedroviruses[NPVs]), Betabaculovirus (lepidopteran-specific Granuloviruses [GVs]),Gam mabaculovirus (hymenopteran-specific nucleopolyhedroviruses) andDeltabaculovirus (dipteran-specific nucleopolyhedroviruses). Of thesegenera, the most important ones for the purpose of the present inventionare the two genera: nucleopolyhedroviruses (NPVs) and granuloviruses(GVs).

GVs contain only one nucleocapsid per envelope, and NPVs contain eithersingle (SNPV) or multiple (MNPV) nucleocapsids per envelope. Theenveloped virions are further occluded in a granulin matrix (GVs) or ina polyhedrin matrix (NPVs). Furthermore, GVs have only a single virionper granulin occlusion body while polyhedra can contain multipleembedded virions.

The baculoviruses tend to have a narrow host arthropod range, that is tosay, insect range, and infectivity is restricted to the original hostgenus or family. Baculoviruses have the additional advantage of beingsubstantially non-toxic to vertebrates such as mammals, includinghumans, and are generally not known to be toxic to beneficial insects,birds or to aquatic organisms.

Compositions comprising baculovirus for use in controlling insect pestsare known in the art. U.S. Pat. No. 6,521,454 provides an insecticidalcomposition comprising (a) a baculovirus effective for producing alethal or debilitating infection in an insect and (b) at least 1 mM of adivalent cation.

However, one of the problems with baculoviruses, and for the purposes ofthe present invention the NPVs and GVs in particular, is that they aresusceptible to UV degradation, typically showing a field persistence oncrops of 2-7 days post application when applied in conventionalcommercial formulations. This problem was partially addressed in US2014/086969 which discloses UV-resistant gelatin/silica coated viralparticles and methods for controlling agricultural insect pests usingthe same.

Baculoviruses are also known to be temperature sensitive. Certainbaculoviruses, such as the NPV of Mulberry have been shown to bevulnerable to temperatures of 50° C., at which temperature they areinactivated and can no longer infect and kill target arthropods(Priyadharshini & Narayanaswamy (2012) EJBS 5(1) pp 22-26. Otherbaculoviruses have been shown to be vulnerable to temperatures of 60° C.or higher, such as the Codling moth virus (Pemsel M. et al (2010) TheJournal of Supercritical Fluids, 53, 174-178). The susceptibility ofviruses of use in the invention to heat has resulted in the creation ofvirus encapsulation methods in the prior art that result in particlesthat employ gas saturated solutions in which the temperature has beenkept low, that is to say below 60° C. (Pemsel et al ibid). WO 96/01055describes a general encapsulation method and product thereof for use inpreparing food products. In more detail, a food product is disclosedcomprising a matrix of fibres having inclusion bodies dispersed therein.

A further problem associated with conventional commercial formulationsis that the virus of choice is typically suspended in naked form in anaqueous formulation which contributes to limiting or reducing theshelf-life of the virus through the action of oxidative processes.

There exists a need to provide more UV-stable formulations of viralagent of choice for use on crop plants. There exists a further need toprovide formulations in which the virus of choice is less susceptible tooxidation.

A further need is to provide improved formulations containing viralagents of choice for use in the field, that is to say on growing cropsand/or on harvested or ‘cut’ produce, and in the storage of foodincluding processed dried comestibles, grains, and processed productsderived therefrom.

A perceived advantage of the present invention is to provide pesticideformulations that persist longer in the field and/or in storage thancurrently known formulations comprising baculoviruses.

A further perceived advantage of the present invention is to provideimproved pesticide formulations comprising baculoviruses of choice thatenable the control of pest larvae on plants which secrete plantchemicals on their aerial structures as a defence against plant viruses,such as legumes e.g. chick peas. Such plant secretions can reduce theeffectiveness of a biological agent of choice if it is applied usingconventional formulations (Stevenson, D'Cunha & Grzywacz, J Chem Ecol.2010 February; 36(2):227-35. doi: 10.1007/s10886-010-9748-8. Epub 2010Feb. 10).

These and other needs and advantages will become apparent from thefollowing description and examples.

As a first aspect of the invention there is provided a compositeparticle comprising:

i) at least one baculovirus particle; and

ii) an enveloping coating of wax for the baculovirus particle of i) madeup of at least one wax that is degradable and/or soluble in the gut of alarva of an arthropod species; and

iii) optionally, an insecticide that is ingestible by an insect larva,such as a pyrethroid and/or an organophosphate.

Naturally, the skilled addressee will understand that for the purposesof the present invention ‘composite particle’ refers to an individualparticle. Such individual particles may be brought together forming apopulation of particles for use in application to crops and/or foodproduce. Such populations of particles may be in liquid or dry powderform depending on end purpose as outlined herein.

The virus particle may be selected from baculovirus particles of speciesof interest, such as from alphabaculoviruses and/or betabaculoviruses,namely, nucleopolyhedrosis viruses (NPVs) and/or granulosis viruses(GVs). Preferably, the baculovirus particle is in the form of an NPV ora GV baculovirus occlusion body. Suitable virus particles of use in theinvention include baculovirus occlusion particles of NPVs or GVs, suchas those selected from Heliothis zea NPV, Helicoverpa armigera NPV,Spodoptera exigua NPV, Spodoptera littoralis NPV, Spodoptera exemptaNPV, Anticarsia gemmatalis NPV, Lymantria dispar MNPV, Neodiprionabietis NPV, Orygia pseudotsugata NPV, Neodiprion lecontei NPV,Trichoplusia ni NPV, Autographa californica NPV, Spodoptera albula NPV,Spodoptera litura NPV, Cydia pomonella GV, Plutella xylostella GV,Cryptophlebia leucotreta GV, Phthorimaea operculella GV, Adoxphyes oranaGV, Homona maganima GV, Plodia interpunctella GV, Adoxophyes honmai GVand the like. Preferably, the viral biological agent is selected fromHeliothis zea NPV, Helicoverpa armigera NPV, Spodoptera exigua NPV,Spodoptera littoralis NPV, Spodoptera exempta NPV, Anticarsia gemmatalisNPV, Cydia pomonella GV and Plodia interpunctella GV depending onpurpose and proposed application in the field. Occlusion bodies of NPVbaculoviruses are of the order of 0.15 μm to 15 μm in length and thoseof GV baculoviruses are of the order of 170-500 nm in size, depending onspecies. The virions of NPV species are of the order of 230-420 nm inlength while those of GV species are of the order of 260 nm-500 nm inlength.

The virus particle is at least partially enveloped or encapsulated inwax. It is thought that the degree of envelopment or encapsulation ofindividual virus particles of use in the invention by a suitablewax-containing material should be a minimum of at least 30%, preferablyat least 50% and preferably still at least about 80%, 90% or 95%. Mostpreferably, the virus particle of choice of use in the invention isfully enveloped in a wax or a blend of waxes that is capable of beingbroken down or degraded and/or solubilised in the gut of a target pestlarva and/or larvae. For the purposes of the present invention the words‘larva’ and ‘larvae’ used herein refer to insect larvae of species thatprey on domestic crops, plants of commercial benefit to mankind andplant products whether processed or otherwise that are derived fromplants such as wood, dry comestibles, and clothing materials includingthose referred to herein. The words ‘larva’ and ‘larvae’ are usedinterchangeably unless context demands otherwise. The envelopment by waxshields the virus particle of choice from exposure to UV and otherenvironmental hazards, such as oxidising conditions. Suitable waxesinclude those that solubilise or degrade or surface etch enough torelease at least one viable virus particle in a larval gut environment,for example, in a basic pH. Such waxes are typically selected fromnatural waxes that are ingestible by larvae, such as carnauba wax, ricebran wax, candelilla wax, sugar cane wax, ouricouri wax, syntheticwaxes, such as amide waxes, polyethylene waxes, functionalisedpolyethylene waxes, oxidised polyethylene waxes and the like that areingestible by the larva or a mixture or blend of two or more thereof. Ifa blend of two waxes is used the waxes may be employed in a ratio of1:99 to 99:1, preferably a ratio of 5:95 to 95:5, or any suitable ratiothereinbetween, such as a 50:50 blend of natural waxes, for example ofrice bran wax and candelilla wax. In certain circumstances, ingestiblewaxes may be made up of a hard wax, for example, carnauba wax or montanwax and at least one softer wax that is ingestible by larvae of speciesof interest such as a natural or synthetic wax as described herein forexample, candelilla wax, rice bran wax or a blend thereof may be furtherblended together. The purpose of adding a hard wax to softer waxes inblends of waxes of use in the invention is to optimise millingprocedures. The waxes may also include an added feed stimulant such assugars, for example, sucrose, fructose, palm sugar, golden cane syrupand the like admixed therein in particulate or liquid form, molasses,honey, sorbitol or other artificial or organic baits (Ballard J et al.,Biocontrol Science and Technology, volume 10, Issue 5 pp 627-640 2000DOI:10.1080/095831500750016424), including volatiles selected fromalcohols, esters and aromatic compounds, such as ethyl acetate,3-methylbutanol, ethyl hexanoate, 2-phenylethanol, ethyl octanoate,ethyl (E)-4-decenoate, ethyl decanoate, ethyl dodecanoate and the like(EI-Sayed A. M. , J. Agric. Food Chem., 2005, 53 (4), pp 953-958 DOI:10.1021/jf048521j), or other plant extracts or a larvae attractant, suchas a larvae aggregation pheromone, for example that of Cydia pomonella(Jumean et al. (2004), The Canadian Entomologist, vol. 136, pp.871-873). Further additives that may be added to or included incomposite particles of the invention include Neem oil, and/orazidirachtin which may synergise with the virus (Nathan and Kalaivani,(2005), Biological Control, 34(1) pp.93-98).

In addition, a wax that may be used in the present invention can be madeup of several different waxes melted to form a liquid or melded togetherunder pressure or heat using a temperature sufficient to soften thewax(es) such that baculovirus particles of choice may be added and atleast partially encapsulated therein. Once the baculoviral agent ofchoice is added to the wax, the wax may be cooled to solidity quicklyand then kibbled, comminuted and/or air jet milled to a desired particlesize using conventional equipment and procedures known in the art.

Such additional waxes may be selected from mineral waxes and syntheticwaxes provided that at least one wax, preferably a natural wax or ablend of natural waxes as described herein, that is degradable and/ordigestible in the larval gut (e.g. through enzyme digestion and/or beingsoluble in a larval gut environment of pH 8 to 12 in the gut of a larvaof interest) is in the melt or mixture and the baculoviral agent is ableto be released from wax blends in the gut of the larva. Typically,natural waxes of use in the invention have a melting temperature of ≥40°C., depending on design. Suitable natural waxes of use in the inventioninclude waxes having a melting point of preferably ≥50° C., and mostpreferably are made up of hard waxes having a melting point of ≥70° C.Examples of natural waxes of use in the present invention includecarnauba wax, beeswax, Chinese wax, shellac wax, spermaceti wax, myricylpalmitate, cetyl palmitate, candelilla wax, castor wax, ouricury wax,wool wax, sugar cane wax, retamo wax, rice bran wax and the like.

Synthetic waxes that may be melted together with or melded underpressure with natural waxes soluble in the gut of a target larva includewaxes selected from paraffin wax, microcrystalline wax, polyethylenewaxes, Fischer-Tropsch waxes, substituted amide waxes, polymerizedα-olefins and the like, provided always that the target larva is capableof ingesting such synthetic waxes. Further waxes that may be meltedtogether with or melded under pressure with natural waxes degradable inthe gut of a target larva include mineral waxes selected from montan wax(e.g. Lumax® Bayer) ceresin wax, ozocerite, peat wax and the like,provided always that the target larva is capable of ingesting suchmineral and/or synthetic waxes and that the partially encapsulated orwholly encapsulated virus particles of choice are releasable therefrom.

An optional component in the form of a pyrethroid or an organophosphateinsecticide may be added to composite particles of the invention toimprove the efficacy of virus control of insect species of interest,such as Lepidopteran species of interest. Suitable insecticides that maybe added to composite particles of the invention containing baculovirusparticles of interest include α-cypermethrin, λ-cyhalothrin,[cyano-(3-phenoxyphenyl)-methyl]-3-(2,2-dibromoethenyl)-2,2dimethylcyclopropane-1-carboxylate(deltamethrin), i-fluvalinate, pirimiphos methyl, chlorpyriphos,malathion, terbufos, phosmet, tiamethoxam, clothiandin, acetamiprid,spinosad, rynaxapyr and the like.

Arthropod species which may be targeted by composite particles of theinvention include crop pest species of the Lepidoptera, pest species ofthe Diptera, and pest species of the Coleoptera such as of theScarabaeidae. The insect pests that may be targeted using compositeparticles of the invention are typically members of the Lepidoptera andinclude the larvae of Lepidoptera species that infest food processingand food storage sites, such as Tobacco moth also known as Warehousemoth (Ephestia elutella), Mediterranean Flour moth (Ephestia Kuehniella)[also known as ‘Indian Flour moth’ and ‘Mill moth’], Raisin moth (Cadrafigulilella), Almond Moth (Cadra cautella) and Indian Meal moth (Plodiainterpunctella). Other insect pests that infest growing crops which maybe targeted using composite particles of the invention include thelarvae of Corn earworm also known as the tomato fruitworm or Tobaccobudworm [Helicoverpa zea], Cotton bollworm, Podborer [Helicoverpaarmigera], Beet armyworm [Spodoptera exigua], Egyptian cotton leafworm[Spodoptera littoralis], African armyworm Spodoptera exempta, Velvetbeancaterpillar [Anticarsia gemmatalis], Gypsy moth [Lymantria dispar],Codling moth [Cydia pomonella], Diamond back moth [Plutella xylostella],False Codling moth

[Thaumatotibia ieucotreta],Potato tuber moth [Phthorimaea operculella],Summer fruit tortrix moth [Adoxphyes orana], Oriental tea tortrix moth[Homona magnanima], and Smaller tea tortrix moth, [Adoxophyes honmai].

In a further aspect of the invention there is provided a method ofproducing composite particles of the invention by:

i) melting at least one wax;

ii) adding baculovirus particles to the molten wax of i) and admixingtherewith for a time period sufficient to at least partially coat thevirus particles;

iii) rapidly cooling the product of ii) to a solid; and

iv) kibbling and comminuting the product of iii) to a particle size foringestion by a larva.

In step i), the wax may be a single wax or a mixture of waxes asdescribed herein. The wax of i) may be melted forming a liquid phase towhich virus particles of choice, for example baculovirus particles suchas occlusion bodies, are then added and admixed therewith in step ii) toform a homogeneous mixture using a high energy mixer, before rapidlycooling down the product of ii) to a solid form. The cooling step iii)is rapidly achieved, for example, by pouring the liquid admixture of ii)into a large shallow tray or other suitable receptacle that is thenplaced inside a suitable freezing means, such as a freezer, and held ata temperature in the range of about minus 5° C. to minus 30° C., such asat minus 24° C. Further means to attain rapid melting in i) and coolingof the product of ii) in step iii) includes the use of commerciallyavailable mantle vessels, such as the Style D kettle with super jacketavailable from Lee Industries, Philipsburg, USA, that are capable ofheating admixtures of the invention to high liquefying temperatures andthen rapidly cooling them to an intermediate temperature, such as themelting temperature of the blend, prior to pouring the cooled liquidinto a receptacle such as a tray and refrigerating further, forming asolid body of wax. It has surprisingly been found that baculovirusparticles, such as baculovirus occlusion bodies, are able to withstandhigh extremes of temperature for short periods of time withoutsignificant loss of viability. Baculovirus particles have been shown bythe inventors to withstand and survive heating temperatures of up to140° C. for short periods of time, for example for up to 5 minuteswithout significant detriment to viability. Furthermore, the inventorshave found that viruses are able to withstand and survive lowtemperatures, for example low temperatures down to about minus 25° C.for short periods of time of up to 12 hours or so, preferably of periodsof time of 1 to 5 hours, for example, 1 to 2 hours, and remain viablethereafter. It is the unexpected finding that baculovirus particles aresurprisingly resilient to temperature extremes that make the presentinvention possible since prior to making the invention it was thoughtthat baculoviruses were not capable of withstanding temperatures above50° C. and so using a liquid wax-based formulation to encapsulatebaculoviruses was not considered feasible.

Once the cooling step of iii) is completed, the resultant block of waxmay then be kibbled, comminuted and micronized to particle sizes of adesired volume mean diameter such as in the range from 1 μm to 200 μm,preferably from 1 μm to 100 μm, more preferably from 1 μm to 50 μm,still more preferably from 2 μm to 40 μm, for example, from 5 to 30 μm,8 to 15 μm and most preferably from 10 to 15 μm as outlined herein.

Particle size is suitably measured using methods and apparatusrecognized as standard in the art. Particle sizing in dispersions can beaccomplished using a variety of techniques, including laser diffraction,dynamic light scattering (DLS), disc centrifugation, and lightmicroscopy. All of these techniques have their advantages andlimitations. Laser diffraction relies on a well-controlled presentationof the sample to the measurement region and is limited to samples withnarrow range of particle concentrations. Dilution is often required andthis may affect the particle size, particularly in compounds with highsolubility. Examples of sizing equipment are made by Malvern Instruments(UK), using laser diffraction methods. For highly irregular particles,the diameter refers to the greatest diameter in any dimension even ifthe particle is relatively non-spherical.

The skilled addressee will appreciate that where composite particles ofthe invention are produced according to this aspect of the invention achemical pesticide may be added to the molten wax of step i), above.Suitable chemical pesticides include those selected fromorganophosphates and pyrethroids such as α-cypermethrin, λ-cyhalothrin,[cyano-(3-phenoxyphenyl)-methyl]-3-(2,2-dibromoethenyl)-2,2-dimethyl-cyclopropane-1-carboxylate(deltamethrin), τ-fluvalinate, pirimiphos methyl, chlorpyriphos,malathion, terbufos, phosmet, tiamethoxam, clothiandin, acetamiprid,spinosad, rynaxapyr and the like.

In a further aspect of the invention there is provided use of compositeparticles as defined herein in the control of larval infestation on cropplants in the field preferably in the reduction of viable numbers oflarvae on crop plants. Use on crop plants in the field includes use onfruit trees, such as apple, pear, cherry and peach trees, crucifervegetables such as cabbage, broccoli, brussels sprouts and kale, cerealssuch as corn (maize), wheat, rye, barley and sorghum, rice, nut treessuch as almond, pecan, hazelnut, brazil, and cashew, grape vines,evergreen trees such as Douglas fir, Loblolly pine, cotton, beans suchas velvet bean, solanaceous species such as potato, tomato, eggplant,capsicum, tobacco and petunia.

Composite particles of the invention may be used prophylactically on orin harvested and/or processed crop produce to minimise the risk ofinfestation by Lepidopteran pests. Harvested and/or processed cropproduce in dried form may be located in storage areas such as grainstorage areas, including grain silos and grain bins where grain isstored immediately after harvest or prior to processing. Other driedfood and grain storage areas include warehouses where dried food andgrain is stored prior to shipment, and transport facilities such asthose of shipping containers, the holds of ships, trucks and the like.Use on harvested and/or processed crop produce includes use on driedcommodities including whole grains such as wheat, rice, barley and corn(maize), pulses, beans, and lentils and products derived from or madewith dried commodities such as processed foods including pasta, grainflours, couscous, breakfast cereals, dried herbs, domestic livestockfeed, for example for pigs, cows, sheep and horses, semolina, breads,nuts (ground, flaked and/or whole nuts), snacking food, such as sweetand savoury items including biscuits, potato crisps, vegetable crisps,pretzels, cheese biscuits, and dried wafers.

In a further aspect of the invention there is provided a composition forapplication to crop plants that comprises composite particles asdescribed herein. Such compositions may be comprised of particles in aliquid medium, that is to say, in the form of a suspension. Thus, as onealternative, there is provided a liquid formulation for controllingarthropod infestation of plants that comprises composite particles,wherein the liquid formulation is made up of:

i) particles of wax suspended within the liquid formulation that aredegradable and/or soluble in the gut of larvae of at least one targetarthropod species; and

ii) at least partially encapsulated within the wax particles of i) atleast one species of baculovirus in the form of baculovirus particlesthat has activity against the larvae of the target arthropod species ofi); and

iii) optionally, an insecticide selected from a pyrethroid and/or anorganophosphate as defined herein. The liquid formulation of theinvention typically has a volume mean diameter in the range from 1 μm to200 μm, preferably from 1 μm to 100 μm, more preferably from 1 μm to 50μm, still more preferably from 2 μm to 40 μm, for example, from 5 to 30μm, 8 to 15 μm and most preferably from 10 to 15 μm as outlined herein.

The virus particles of use in liquid formulations of the invention areat least partially enveloped or encapsulated in waxes of choice asoutlined herein. It is thought that the degree of envelopment orencapsulation of individual virus particles by a suitable wax-containingmaterial of use in liquid formulations of the invention should be aminimum of at least 30%, preferably at least 50% and preferably still atleast about 80%, 90% or 95%. Most preferably, the virus particle ofchoice of use in the invention is fully enveloped in a wax or a blend ofwaxes that is capable of being broken down or degraded and/orsolubilised in the gut of a target pest larva and/or larvae.

The particles of the invention may be applied using either an aqueousliquid or an oleaginous liquid. In either format, the skilled addresseewill appreciate that liquid compositions of the invention comprisecomposite particles that at least partially encapsulate and protect thevirus particles from environmental elements such as UV light andoxidation. Preferably, the virus particles are fully encapsulated by thewax or wax admixture of the composite particles.

The liquid formulation of the invention may be formulated as an aqueousformulation or as an oleaginous formulation, depending on design.Aqueous formulations may include surfactants selected from commerciallyavailable ranges of surfactants sold under the trade marks such asLibsorb, Silwet, Tween, Span, Tensiofix, Brij, Torpedo, Newmans,Lansurf, Atplus, Atlox, Synperonic, Fortune, Guard, Rhino, Biopower, andthe like. Of these surfactants, Tensiofix, and Span are most preferred.

Liquid formulations of this aspect of the invention may includeadditional feeding stimulants in liquid or solid form, as describedhereinabove.

The liquid formulations according to this aspect of the invention may beapplied to eukaryotic tissue selected from plant tissue, such as leaves,stems, fruiting bodies, and flowers.

Oleaginous formulations, that is to say oil dispersion (OD)formulations, may contain any oil suitable for use in the inventionwhich may be selected from petroleum oils, such as paraffin oil, summerspray oils, the solvesso® range of solvents, petroleum spirits andwinter spray oils known in the art, and vegetable oils such as rapeseedoil, soybean oil, sunflower oil, palm oil and the like.

Composite particles of the invention once delivered to target surfacesare capable of adhering thereto, as the aqueous element of thecomposition evaporates or, in the case of an oleaginous element, the oildisperses and are available for ingestion by the feeding target larvae.The degree of encapsulation or envelopment of the biological agent ofchoice should be such as to protect the biological agent fromenvironmental elements as alluded to herein. Target eukaryotic cellsurfaces include plant surfaces of living plant tissue such as growingplants and harvested or ‘cut’ material, for example, leaves, stems, andflowers where target insect larvae may be found.

The composite particles of the invention as applied in liquidcompositions should be effective in controlling populations of plantinfesting target insect larvae through ingestion by the target larvae.The baculovirus particles of use in the invention must be capable ofbeing released from composite particles of the invention inside thetarget larvae gut, and once released, be capable of killing the larvae.

The liquid compositions of the invention may include more than onebaculovirus particle, for example a target larvae specific baculovirusas hereinbefore described and a further baculovirus particle, both ofwhich have the capacity of controlling the infesting population oftarget pest larvae. Thus, compositions of the invention comprisingcomposite particles of the invention carrying two different baculovirusparticles of choice may be more efficient at killing target larvae.Thus, a single liquid composition of the invention may comprisecomposite particles of the invention that are loaded with at least twodifferent baculovirus particles of the same or different species ofchoice that are capable of targeting the target pest larvae. Or, in analternative, liquid compositions of the invention may include two ormore composite particles wherein each composite particle is furtherloaded with different chemical pesticides selected from anorganophosphate and a pyrethroid which are capable of targeting pestlarvae. The chemical pesticide, if present, is typically added while thewax is in the molten state along with the baculovirus particle.

In a further aspect of the invention there is provided a dry powdercomposition that is effective in controlling arthropod infestation instorage products that comprises composite particles, wherein the drypowder composition is made up of:

i) particles of wax that are degradable and/or soluble in the gut oflarvae of at least one target arthropod species; and

ii) at least partially encapsulated within the wax particles of i) atleast one species of baculovirus in the form of baculovirus particlesthat has activity against the said arthropod larvae; and

iii) optionally, an insecticide selected from a pyrethroid and/or anorganophosphate as defined herein.

The particles of wax in the dry powder composition of the inventiontypically have a volume mean diameter in the range from 1 μm to 200 μm,preferably from 1 μm to 100 μm, more preferably from 1 μm to 50 μm,still more preferably from 2 μm to 40 μm, for example, from 5 to 30 μm,8 to 15 μm and most preferably from 10 to 15 μm as outlined herein.

The virus particles of use in dry powder compositions of the inventionare at least partially enveloped or encapsulated in waxes of choice asoutlined herein. It is thought that the degree of envelopment orencapsulation of individual virus particles by a suitable wax-containingmaterial of use in dry powder compositions of the invention should be aminimum of at least 30%, preferably at least 50% and preferably still atleast about 80%, 90% or 95%. Most preferably, the virus particle ofchoice of use in dry powder compositions of the invention is fullyenveloped in a wax or a blend of waxes that is capable of being brokendown or degraded and/or solubilised in the gut of a target pest larvaand/or larvae.

The skilled addressee will appreciate that composite particles of theinvention whether applied as dry powders or as liquid formulations maycontain other desirable components such as additives selected from UVblockers such as oxyl methoyxcinnimate, modified soya oil, zinc oxidenano-particles, beta-carotene or p-amino benzoic acid, colouring agentssuch as optical brighteners and commercially available colouring agentssuch as food colouring agents, plasticisers such as glycerine or soyoil, antioxidants such as vitamin E, butylated hydroxyl anisole (BHA),butylated hydroxytoluene (BHT), and other antioxidants that may bepresent, or mixtures thereof. The skilled artisan will appreciate thatthe selection of such commonly included additives will be made dependingon end purpose. The skilled addressee will further appreciate that anyadditives to the composite particles of the invention should be onesthat do not significantly interfere with the ability of the targetlarvae to ingest the particles.

In an alternative, composite particles of the invention may be presentedto crop plants or harvested and/or processed crop produce as a drypowder.

In a further aspect of the invention, there is provided a method ofcontrolling arthropod infestation, preferably in reducing arthropodinfestation on grain or on processed comestibles wherein dry compositeparticles according to the invention are presented to the surfaces ofgrain or processed comestibles by

i) collecting the composite particles in a dusting apparatus;

ii) releasing the said particles from the said dusting apparatus andonto the surfaces of said grain or processed comestibles.

In a further aspect of the invention, there is provided a method ofcontrolling arthropod infestation, preferably in reducing arthropodinfestation on grain or on processed comestibles wherein dry compositeparticles according to the invention are admixed with grain or processedcomestibles.

In a still further aspect of the invention, there is provided a methodof controlling arthropod infestation, preferably in reducing arthropodinfestation in a storage area selected from a grain storage area and adried food storage area wherein dry composite particles according to theinvention are presented to the surfaces of the storage area by

i) collecting the composite particles in a dusting apparatus;

ii) releasing the particles of i) from the dusting apparatus and ontothe surfaces of the storage area.

In a further aspect of the invention there is provided a crop plant orcut harvested produce coated with particles as defined herein.

There now follow examples that illustrate the invention. It is to beunderstood that the examples are not to be construed as limiting theinvention in any way.

EXAMPLES SECTION Introduction

This work describes the method required to formulate virus in waxparticle formulations. Key:

BV: Baculovirus Occlusion Bodies raw material

NPV: Nucleopolyhedrovirus, a genera of the baculoviridae family ofviruses included under the BV umbrella

GV: Granulovirus, a genera of the baculoviridae family of virusesincluded under the BV umbrella

EBV: Baculovirus occlusion bodies formulated into Entostat® particlesthrough the methods described below

EBV+: Baculovirus occlusion bodies formulated into Entostat® particlesthrough the methods described below, which also contain other additivesof the types described previously in this document such asphagostimulants and aggregation pheromones.

-   1. Materials:

Active ingredient (BV of the chosen species—SpliNPV targeting Spodopteralittoralis, or the Egyptian cotton leaf worm) sourced from NRICandelilla wax and Rice bran wax.

-   2. Equipment:

Hotplate that heats up to 150° C. (Stuart scientific Ltd)

Two decimal place balance (Ohaus®)

Freezer that cools down to at least −24° C. (any make/model will do)

High shear mixer/homogenizer (IKA® T18 digital)

Kibbler mill (KT handling limited model 04)

Comminuting mill (Apex® LTD type 314s)

Air jet mill (any make/model will do)

Suitable size sample pots

-   3. Detailed Procedure-   3.1. Using a calibrated balance weigh out the required quantity of    carrier waxes—125.0 g of rice bran wax and 125.0 g of candelilla    wax.

Place a 50:50 mixture candelilla wax: rice bran wax (% w/w) into a panand place onto a hotplate set to a temperature of 120° C. The wax isheated until completely melted and a clear liquid with no solids isobserved.

Using a calibrated balance a quantity of the active BV at 1% w/w isweighed out.

-   3.1.1. The BV is added to the molten wax quickly over a total time    period of 60 s and dispersed within the molten wax by high shear    mixing (using a high shear mixer IKA® T18) to ensure even    distribution within the wax.-   3.2. The wax is then transferred to a foil lined shallow tray and    transferred to a freezer set at −24° C. to rapidly cool and solidify    within approximately 1-2 h.-   3.3. Once the formulated material is frozen into a completely solid    block or slab it is broken into large chunks and sent for milling.    The chunks are ground in a kibbler mill (KT Handling Limited,    Model 04) to particles of approximately 2 mm average diameter-   3.4. The kibbled material is then comminuted into smaller particles    in a comminuting mill (model 314s, from Apex® Ltd) to particles of    150 μm average diameter.-   3.5. The comminuted material is further micronized in a jet mill    (Hosokawa® Alpine Jet AFG 100 fluidised bed jet mill) to achieve    granulation of mean average particle size ˜10 um.-   3.6. The micronized material containing baculovirus particles (EBV)    is stored in a suitable sample container under refrigeration    conditions at 4° C., until use.

Bioassay Methods

The efficacy of the different EBV formulations is tested using twomethods—the droplet method, using young neonate larvae, and thediet-plug method, using older (L3) larvae. All experiments will uselarvae of the Egyptian cotton leafworm (Spodoptera littoralis).

Droplet method: EBV formulations are added to 10% sucrose solutioncontaining food dye and a wetting agent (e.g. 1% Lankem AEP 66). Adilution series provides six EBV concentrations to provide reliablecomparisons of LC50 values across different formulations (i.e. theconcentration of EBV required to achieve 50% mortality). As positive andnegative controls, the EBV concentrations are compared against the LC50dose of the non-formulated SpliNPV virus, and the solution without anyvirus (i.e. sucrose solution, dye and wetting agent alone). For thebioassay, starved neonate larvae are placed in the centre of a Petridish containing concentric circles of droplets of EBV solution. After 30min feeding, larvae with blue guts (indicating that they have ingestedthe solution) are removed and placed singly into diet pots in anincubator at 27° C. Twice-daily monitoring of the larvae provides dataon timing of death (or pupation) and its cause—larvae dying of viralinfection are easily diagnosed visually, but is confirmed by microscopy.Bioassays use 50 larvae per treatment at each virus concentration, andthe LC50 values of each EBV are calculated from five replicate assaysusing logistic regression.

Diet plug method: Starved 3rd-instar larvae are presented individuallywith a small cube (2 mm³) of semi-artificial diet laced with 2 ml of therequisite EBV solution (or control solution) and left in an incubatorovernight and next morning, larvae that have not eaten all of the dietplug are discarded. The remainder of the larvae are moved intoindividual diet pots and again monitored twice-daily formortality/pupation. Sample sizes and analytical methods are the same asfor the droplet bioassay.

Testing Effects of UV on EBV and EBV⁺ Formulations

Trial EBV and EBV⁺ formulations are tested initially in a sunlightsimulator to quantify the effects of UV on the viability of thedifferent EBV formulations compared to non-formulated virus and currentcommercial formulations (e.g. Littovir™). The EBV is exposed as driedsuspensions of virus on mylothene laminated sheets—a system that hasbeen developed at University of Greenwich to mimic plant leaf exposures.They are then exposed for 24 h to a Nereus CPS laboratory sunlightsimulator which produces a UV spectrum comparable to sunlight. The testsamples are cooled underneath by circulating temperature-controlledwater. Exposed virus is then washed using a standard recovery protocol(sonication for 3 min then by wash for 1 h in 0.2% sodium dodecylsulphate) to extract the exposed virus for neonate bioassay at LU.Promising candidate EBV⁺ are identified, longer-term (0-30 day)evaluations are carried out in UV weathering equipment, simulating bothtropical and temperate cropping conditions with respect to UV,temperature and humidity levels. All treatments are applied using adroplet sprayer to mimic field application. The UV stability of the mostpromising EBV⁺ is compared to both non-formulated virus andcommercially-formulated viruses. Targets are exposed to sunlightday-night cycles, and EBV⁺ samples are harvested at 0, 1, 2, 4, 8, 16 &32 days for virus recovery. Exposed EBV⁺ is then neonate bioassayed atLU to determine biological activity and EBV⁺ half-life. Physicalcharacteristics of exposed EBV⁺ are also determined by SEM.

Quantifying Persistence of EBV and EBV⁺ Formulations on the Crop

The persistence of the candidate EBV and EBV⁺ formulations is determinedon two representative crop species: tomato and cabbage, grown in aglasshouse. Mature plants (30 per treatment) are sprayed with one of 2rates of EBV⁺ solution (based upon commercial field application rates,validated via pilot studies), or with the EBV⁺ carrier alone (i.e.water+wetting agent; negative control) or the non-formulated SpliNPVvirus solution (+wetting agent; positive control) or a commercialSpliNPV biopesticide (e.g. Littovir™) Immediately post-spraying, andthen after 1, 2, 5, 10 or 20 days, a subset of plants is harvested forbioassays. Small disks (1 cm diameter) of leaf from sprayed plants arefed to starved third-instar larvae overnight in an incubator (27° C.).Larvae that have eaten all of the leaf the next morning are thentransferred to a diet pot and their mortality/pupation monitored twicedaily (30 larvae per sampling point per treatment group). In addition,and building on initial assessments made during EBV⁺ selection, at eachsampling point the condition of the host plants used in the differenttreatments is compared to establish whether there are any short- orlong-term negative effects of the UV blockers. Traits to be quantifiedinclude plant height, plant dry mass (above- and below-ground), leafarea and leaf colour.

The persistence of baculovirus particles of the invention is shown to besuperior when compared to that of conventional formulations containingbaculovirus.

1-48. (canceled)
 49. A composite particle comprising: i) at least onebaculovirus particle; and ii) an enveloping coating of wax for thebaculovirus particle of i) made up of at least one wax that isdegradable and/or soluble in the gut of a larva of an arthropod species,wherein the baculovirus particle is completely enveloped by the coating.50. A particle according to claim 49 further comprising an insecticide.51. A particle according to claim 49, wherein the baculovirus particleis selected from an alphabaculovirus particle and a betabaculovirusparticle.
 52. A particle according to claim 49, wherein the baculovirusparticle is in the form of a baculovirus occlusion body.
 53. A particleaccording to claim 49, wherein the baculovirus particle is selected fromHeliothis zea NPV, Helicoverpa armigera NPV, Spodoptera exigua NPV,Spodoptera littoralis NPV, Spodoptera exempta NPV, Anticarsia gemmatalisNPV, Lymantria dispar MNPV, Neodiprion abietis NPV, Orygia pseudotsugataNPV, Neodiprion lecontei NPV, Trichoplusia ni NPV, Autographacalifornica NPV, Spodoptera albula NPV, Spodoptera litura NPV, Cydiapomonella GV, Plutella xylostella GV, Cryptophlebia leucotreta GV,Phthorimaea operculella GV, Adoxophyes orana GV, Homona maganima GV,Plodia interpunctella GV, and Adoxophyes honmai GV.
 54. A particleaccording to claim 49, wherein the wax is selected from waxes that areingestible by a larva.
 55. A particle according to claim 49, wherein thewax is a natural wax that is degradable and/or soluble in the gut of alarva.
 56. A particle according to claim 49, wherein the wax is amixture of waxes selected from mineral waxes and synthetic waxes and atleast one natural wax wherein at least the natural wax is degradableand/or soluble in the gut of a larva.
 57. A particle according to claim49, wherein the natural wax is selected from carnauba wax, rice bran waxand candelilla wax and a mixture of two or more thereof.
 58. A particleaccording to claim 49, wherein the arthropod species is a species fromthe order Lepidoptera and wherein the gut of the larvae of the arthropodspecies has a pH from 8 to
 12. 59. A method of producing particlesaccording to claim 49 by i) melting said wax; ii) adding saidbaculovirus particle to the molten wax of i) and admixing therewith fora time period sufficient to at least partially coat the biologicalagent; iii) rapidly cooling the product of ii) to a solid; and iv)kibbling and comminuting the product of iii) to a particle size foringestion by a larva.
 60. A method according to claim 49, wherein theparticles have a volume mean diameter of less than 30 μm.
 61. A methodaccording to claim 49, wherein the particles have a volume mean diameterin the range 8 μm to 15 μm.
 62. A composition for application to cropplants that comprises particles as defined in claim
 49. 63. Acomposition for application to harvested and/or processed crop producethat comprises particles as defined in claim 49 in dry form.
 64. A cropplant coated with particles as defined in claim
 49. 65. A liquidformulation for controlling arthropod infestation of plants thatcomprises composite particles according to claim 49 suspended within theliquid formulation.
 66. A dry powder composition that is effective incontrolling arthropod infestation in storage products that comprisescomposite particles according to claim 49, wherein the dry powdercomposition is made up of: i) particles of wax that are degradableand/or soluble in the gut of larvae of at least one target arthropodspecies; and ii) at least partially encapsulated within the wax partiesof i) at least one species of baculovirus in the form of baculovirusparticles that has activity against the said arthropod larvae.
 67. Amethod of controlling arthropod infestation, wherein dry compositeparticles according to claim 49 are presented to the surfaces of grainor processed comestibles, or surfaces of storage areas by i) collectingthe composite particles in a dusting apparatus; ii) releasing the saidparticles from the said dusting apparatus and onto the surfaces of saidgrain or processed comestibles.
 68. A method of controlling arthropodinfestation, wherein dry composite particles according to claim 49 areadmixed with grain or processed comestibles.
 69. A composite particleaccording to claim 49, further comprising at least one UV blocker.